Method of hardening fresh linings of sulphite-pulp digesters



Feb. 6, 19.23. 1,444,467?

C. H. JONSSQN METHOD OF HARDENING FRESH LININGS OF SULPHITE PULP DIGESTERS Filed. Dwl6, 1.92l

Patented Pe -3J5, i921 CARL HERMAN JOI 'TSSON, OF BORLANGE, SWEDEN.

METHOD OF HARDENING FRESH LININGS F S'U'LPI-IIIIE-PULP DIGES'IERS.

Application filed December 16, 1921. Serial No. 522,863.

siding at Borlange, Sweden, have invented 5 new and useful Improved-lvlethod of Hardening Fresh Linings of Sulphite-Pulp Digesters, of which the following is a specification. I

This invention relates to an improved method of hardening fresh linings of sulphite pulp digesters.

For protecting the walls of sulphite pulp digesters against the corrosive action of the sulphite lye the metal walls of the digester are generally coated with an internal acidproof lining, which is manufactured of acidproof bricks and a mortar which is hardened when subjected to the action of the free sulphurous acid in the lye. Said mortar, which is applied directly on the metal sheets as well as in the joints between the bricks may be of different compositions and may for instance contain calcium-iron-silicates, calcium silicates, calcium monosulphite, lead oxides, lead salts, chamotte meal, potash or soda water-glass, and so on. When a digester had been lined with such mortar and dried, it was hitherto filled with sulphite lye whereupon the free sulphurous acid of the lye reacted with the mortar and caused a successive increase of its hardness and strength. This hardening process proceeds, however, rather slowly and goes on even after that the digester has been taken in use for the manu facture of the sulphite pulp. In the first period of the use of a digester having obtained a fresh lining the latter may easily be damaged if the boiling is performed at normal pressures and with normal speed ere the lining has reached its full stren th. The slowly hardening of the lining makes it, therefore, necessary to reduce the intensity of working for some time after the application of a fresh lining in a digester.

The object of the present invention is to remove said drawback by an improved hardening method by which the mortar of the lining obtains its full strength in a very short time.

The invention consists chiefly in effecting the hardening of the lining by means of sulphurous acid in gaseous state instead of as hitherto by means of a liquid in which the sulphurous acid is dissolved.

I have discovered that the fresh lining of a sulphite pulp digesteris hardened essentially more rapid when using sulphurous acid in gaseous state instead of a solution and that the strength of the lining against wear is also improved.

The sulphurous acid used forjthe hardening process may be obtained in any suitable manner but I prefer to take it from another digester in use, in which case gaseous sulphurous acid and steam of more or less high pressure is drawn off from the latter and introduced in the digester th is to be hardened. In such e lining of which case the gas and steam may be taken from the digester in use either during the 'boiling operation or when the boiling has been finished and the hardening process be combined with the recovery of the sulphurous acid.

In the accompanying drawing I have diagrammatically illustrated one embodiment of my invention.

. Referring to the drawing A and B represent two sulphite pulp digesters, of which A is supposed to be in operation for digesting pulp while the digeste r B is supposed to have obtained a. fresh acid-proof lining. The digesters A and B are at the top connected by a pipe a, 'contalnlng valves E and C. Dis avalve in a bran may be connected to an ch pipe Z2 which acid tank (not shown) and F is valve in a. pipe 0 from the bottom of the digester B. also be connected to the shown.

When the valves E and while the valve D The pipe 0 may acid tank not C are opened is maintained closed gaseous sulphurous acid flows from the digester A through the pipe (4 to the digester B and then through the valve ii to the acid tank not shown where it is store d. As the lining of the digester B is hardened the valve F is successively closed so that the pressure slowly increases in the digester B until the pressure in the latter will be equal to that of the digester A. When the lining of the digester B has been hard ened sufiicien-tly which may be proved by taking up small holes in the metal wall of the digester, the

valve C is closed and the valve F is opened,

the gas contained in the dig ing to the acid tank through the VJ hat I claim is 1. Method of hardening ester then escappipe 0.

fresh linings of acid-proof bricks and mortar in sulphite pulp digesters, consisting i liIHII to the action of sul gaseous state.

11 subjecting the phurous acid in pulp dig phurous acid in gaseous; state. f0 the digester, and successively increasing the pressure of the gas until the lining is harde'lied.

acid-proof bricks and. momma-1% a sulphite l'ntes't-imony whereof I have signed my name. i v

lARL HERMAN JONSSON.

2. Method of hardening fresh linings of id-proof bricks and mortar 111 sulphite esters, consisting 1n supplying sul- Method. of hardening a fresh liningof 

